I also use a woodpeck lift with a DW621. You can adjust the elevation
screw to be less tight and it cranks easier. I couldn't be happier
with the setup. It's super quiet with no noticeable vibration.

For the original poster, if your current router lift is drifting down
then you need to lock the height adjustment on your router. I don't
think most lifts are designed to lock the height in place. Vibration
from the router will make the adjustment screw drift.